Sludge, a thick soft mud or other viscous liquids is typically the byproduct of wastewater treatment; industrial wastewater solids and settled suspension from potable water treatment are handled as hazardous waste. It often contains various types of pathogens as well as heavy metal contaminants and, in the case of industrial waste, chemical pollutants. Sludge contaminated by chemical pollutants or heavy metals, demands complex treatment.
Reducing the volume of sludge and its toxicity into a more convenient form for disposal is the goal of various treatment processes. Stabilization, drying, incineration, thickening and dewatering are some of the basic sludge treatment methods. Drying and incineration in most cases is cost-prohibitive due to the price of fuel and the requisite treatment of the combustion gases.